WELLS AND BUTLER: TUNGSTENITE, A NEW MINERAL 599 



the ore with chlorine in a hot tube. As the analysis stands the 

 sample analyzed consists of 8.1 per cent of tennantite and tetra- 

 hedrite, 17.3 per cent of pyrite, 4.7 per cent of galena, and 61.5 

 per cent of tungstenite. 



The geology of the district in which tungstenite has been found 

 may be briefly summarized as follows: A series of Paleozoic 

 limestones, shales, and quartzites, and pre-Paleozoic quartzites 

 and shales, has been much broken by thrust faulting and subse- 

 quently intruded by quartz monzonite and quartz diorite which 

 occur as stocks. Following the intrusion and accompanying 

 mineralization there was much normal faulting and some reverse 

 faulting. 



The Emma ore body occurs as a replacement of a brecciated zone 

 in Paleozoic limestone where it is crossed by a mineralizing fissure. 

 The ore shoot follows the intersection of the breccia zone and 

 fissure, pitching rather steeply to the northeast. About 450 

 feet below the outcrop the ore shoot is cut off by a strong fault, 

 the continuation on the opposite side of the fault being about 

 250 feet lower. There is very little oxidized material in the 

 portion of the shoot below the fault from which the tungstenite 

 was taken. 



The important vein minerals are quartz, galena, pyrite, tetra- 

 hedrite, argentite, and possibly some other silver minerals not 

 yet determined. The detailed study of the ores will probably 

 reveal other minerals. For a part of the shoot at least, the 

 central portion consists mainly of rather fine-grained quartz 

 that has almost completely replaced the limestone and that con- 

 tains but relatively small amounts of metallic minerals. Sur- 

 rounding this is a zone in which the limestone is less completely 

 replaced and metallic minerals are more abundant. 



Pyrite was the earliest metallic mineral to form in the deposit 

 and this was followed by the galena, tetrahedrite, silver minerals, 

 and tungstenite. The tungstenite is apparently in part con- 

 temporaneous with the galena and in part later than the galena. 

 The fact that the specimens containing the most of this mineral 

 have been found near a minor faulted zone suggests that there 

 may have been an enrichment in tungsten along that zone, 

 though that is not certain. 



